The defenders had fled, and there was no immediate word on the whereabouts of Kadhafi or his family after the insurgents breached the defences as part of a massive assault that began in the morning.

"Rebels breached the surrounding cement walls and entered inside. They have taken Bab al-Azizya. Completely. It is finished," the correspondent said.

"It is an incredible sight," he said, adding that the bodies of a number of apparent Kadhafi fighters were lying inside, as well as wounded.

Only minutes earlier, rebel spokesman Colonel Ahmed Omar Bani said from Benghazi: "Our forces are surrounding Bab al-Azizya. There is a fierce battle going on there. We are now controlling one of the gates, the western entrance."

The correspondent said rebels found an armoury in one of the buildings and were seizing quantities of ammunition, pistols and assault rifles.

There was no immediate comment from the rebel leadership in the eastern city of Bengazi, but an official in the western city of Misrata said that "at the same house used by Kadhafi before to describe the Libyan people as rats, today the independence flag flying on its roof."

Amid reports that ordinary citizens were beginning to stream into the complex of several hectares (acres), rebel television Al-Ahrar called on people to stay away so that insurgent fighters could mop up inside.

It also urged police in Tripoli to remain at their posts in order to guarantee security.

On Tuesday morning, Kadhafi's son Seif al-Islam, who was reportedly under arrest, made a surprise appearance in Tripoli and announced that his father and family were still in the capital.

However, he declined to say where.

"Kadhafi and the entire family are in Tripoli," Seif told reporters at the Rixos Hotel where many foreign journalists are housed.

Seif also said the regime's forces had deliberately not tried to prevent the rebels from entering the capital.

"Allowing the rebels to enter Tripoli was a trick," he said, without elaborating.

NATO, meanwhile, said Kadhafi was "not a target" for the military alliance.

"Kadhafi does not constitute a target," he told reporters in Brussels via video-conference from the mission's Naples headquarters.

In the hours that led up to the storming of the compound in central Tripoli, the sound of the fighting was the most intense heard in the city since rebels arrived three days ago.

The correspondent said rebel forces coming from the western city of Misrata had reinforced the offensive during the afternoon.

The rebel official in Misrata said one of their commanders had been killed in the assault on the compound.

The sky was filled with the sound of heavy and light machine guns as well as mortars, with the overhead roar of NATO jets that had been carrying intensive over flights though it was unclear if there were any air strikes.

Even two kilometres (about a mile) from the fighting, the almost constant whistle of falling bullets could be hear from the rooftops, as the city's mosques chanted "Allahu Akbar" (God is greatest).